Sometimes classified as a superorder

• A group of chiefly woody plants considered among the most primitive of angiosperms
• Contains 23 families including the Betulaceae and Fagaceae (includes the Amentiferae)
• Perianth poorly developed or lacking
• Flowers often unisexual and often in catkins and often wind pollinated

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Hamamelidae \Hamamelidae\ n. a group of chiefly woody plants considered among the most primitive of angiosperms; they have a perianth poorly developed or lacking, and flowers often unisexual and often in catkins and often wind pollinated. The group contains ...